Petrology of Sirdan volcanic rocks in Alborz Mountains, northern Iran

Fatemeh Ghotb-Tahriri, Mohammad-Ali Arian, Shahrooz Haghnazar, Mohsen Pourkermani


The study area is located around Sirdan town in Sofla-Tarum Mountains in Alborz, south west of Manjil City and west of Loshan, northern Iran. Talesh-Western Alborz volcanic belt was formed by the subduction of Neotethys ocean toward north. However, some researchers believe that the continental rift is responsible for its formation. Firstly, geological field trip was carried out and lithogeochemical samples were collected and prepared for chemical and mineralogical studies. Genetic pattern of the samples was also introduced based on the geochemical analysis and microscopic studies. Sirdan volcanic rocks (northern Iran) include pyroclastic and lava units. Lavas are basalt, andesite, trachyandesite, dacite and riolite. Pyroclastic rocks also consist of different kind of tuffs (lattice crystal tuff, halo lattice tuff, sandy tuff, clay tuff and tuffit), ignimbrite and breccia. Age of the formations belongs to tertiary (mostly Eocene to Oligocene). Basic lavas include olivine, clinopyroxene, plagioclase phenocrysts as well as opaque minerals and plagioclase and clinopyroxene microlite. The dominated texture of the samples is porphyritic microlite. Medium-silica lavas have plagioclase-pyroxene, alkali feldspar, and biotite and amphibole phenocrysts. They also have silica and feldspar microlite and the dominated texture is halo porphyritic. Acidic lavas consist of plagioclase, quartz and alkali feldspar phenocrysts with xenocryst of quartz, feldspar and silica with a dominated texture of porphyry with micro-granular and hyaline. Based on the geochemical analysis, the studied rocks are sub alkaline and tholeiitic. Pattern of rare earth elements shows a high contamination of magma with crustal surface. Finally, the tectonic situation of the studied samples have been introduced from mantle with a source of MORB toward the active marginal continental rift.


Sirdan, Iran, Neotethys, crustal contamination, continental active margins

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Alavi, M., 1996, Tectonostratigraphic synthesis and structural style of the Alborz Mountain system in northern Iran. Geodynamic, 21, 1-33.

Berebrian, M., and King, G.C.P., 1981, Towards a paleogeography and tectonic evolution of Iran. Canadian Jounal of Earth Sciences, 18, 210-265.

Cox, K.G., Bell, J.D., and Pankhurst, R.J., 1979, The interpretation of igneous rocks. George Allen and unwin London, London, 450 p.

Didon, J., Gemain, Y. M., 1976, Le Sabalan, Volcan Plio-quaternair de l’Azerbaidjan oriental (Iran); étude géologique et pétrographique de l’edifice et de son environnement régional. Thése de 3éme Cycle, Univ. Grenoble, 304 p.

Emami, M.H., 1981, Géologie de la région de Qom-Aran(Iran). Contribution á l’étude dynamique et géochimique du volcanisme tértiaire de l’Iran central. Thése d’Etat. Univer. Granoble, France, 489 p.

Emami, M.H., 2000, Magmatism in Iran. Geological Survey of Iran, Tehran, 608 p. (In Persian)

Google Earth., 2016, Satellite images.

Innocenti, F., Manetti, P., Mazzuuoli, R., Pasquare, G., and Villari, L., 1982, Anatolia and north-western Iran. In: Thorpe R.S. (ed.). Wiley, J., and Chichester, S., Andesites, orogenic andesites and related rocks. p. 327-349.

Koglin, N., 2008, Geochemistry and petrogenesis and tectonic setting of ophiolites and mafic- ultramafic complexes in the Northeastern Aegean region: New trace-element isotopic and age constraints. Dissertation zur erlangung des grades doktor den naturwissenschaften, Johannes Gutenberg-Universitat, 173 p.

Lescuyer, J.L., Riou, R., 1976, Geologic de la region de mineh (Azerbaijan) Contribution a l’etude du volcanisme tertiaire de l’Iran. These de 3éme Cycle Grenoble, 233 p.

Miyashiro, A., 1978, Nature of alkaline volcanic rock series. Contributions of Mineralogy and Petrology, 66, 91-104.

Moein-Vaziri, H., 1996, An introduction to the Magmatism in Iran, Tarbiyat Moallem University publication, Iran, Tehran, 440 p.

Nabavi, M.H., 1976, An introduction to the geology of Iran. Geological Survey of Iran, Tehran, 109 p. (in Persian)

Nazari, H. and Salamati, R., 1998, Geological Map of Rudbar sheet (1/100000). Geological Survey of Iran, Tehran, 1 p.

Rudnick, R.L. and Fountain, D.M., 1995, Nature and composition of the continental crust: A lower crustal perspective. Reviews of Geophysics, 33, 267-309.

Schandle, E. S. and Gorton, M. P., 2002, Application of high strength elements to discriminate tectonic setting in VMS environments. Economic Geology, 97, 629-642.

Sun, S.S. and McDonough, W.F., 1989, Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. In: Saunders, A.D. and Norry, M.J., (eds) Magmatism in the oceanic basins. Geological Society London Special Publications, 42, 313-345.

Taylor, S. R. and McLennan, S. M., 1985, The continental crust: it's composition and evolution. Blackwell, Oxford, England, 312 p.

Wandji, P., Seuwui, D.T., Bardintzeff, J.M., Bellon, H., and Platevoet, B., 2008, Rhyolites of the Mbépit massif in The Cameroon volcanic line: an early extrusive volcanic episode of Eocene age. Journal of Mineralogy and Petrology, 94, 271-286.

Wilson, M., 1989, Igneous petrogenesis. a global tectonic approach. Unwin Hyman, London, 466 p.

Yousefi-Ilani, Alireza., 2004, Qazvin city roads network map sheet (1/400000), Iran National Cartographic Center, Tehran, 1 p.


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